In his new role, he will spearhead development of unscripted as the company eyes formats with global appeal. Castallo will be heavily involved in Mark Burnett’s “Eco-Challenge” and the upcoming fashion series with Tim Gunn and Heidi Klum. Castallo will report directly to Amazon TV co-heads Albert Cheng and Vernon Sanders.

Castallo was most recently head of development at Verizon’s mobile platform, Go90, until it was shut down in July. He was also a former head of alternative for CBS, where he oversaw reality series including “Survivor,” “Amazing Race,” “Undercover Boss” and “Big Brother” during his 10-year tenure. He was named executive VP of alternative programming in 2013 after previously serving as senior VP.

Schuster’s exit came after an investigation into her corporate conduct, according to Deadline. Citing an unnamed source, the site reported that the investigation stemmed from concerns about Schuster’s verbal behavior. Schuster was named to the position last October, filling the vacancy left by Conrad Riggs during the executive shakeup following the ouster of former programming boss Roy Price.

Last week, Amazon named James Farrell as head of international originals. In the newly created role, Farrell will lead the international originals teams in Japan, India, Europe, Mexico and Brazil, as well as future locales. He’ll report to Jen Salke.

NBC's "Lost"-like vehicle "Manifest" is now second, having averaged 10.4 million overall viewers on its own premiere night. CBS' "God Friended Me" had initially topped that total, though the NFL football-boosted drama adjusted down in final numbers.

Scroll through our gallery for the full rankings of the 20 debuts we've seen thus far. TheWrap will update this post as more new broadcast shows start.

NBC's "Lost"-like vehicle "Manifest" is now second, having averaged 10.4 million overall viewers on its own premiere night. CBS' "God Friended Me" had initially topped that total, though the NFL football-boosted drama adjusted down in final numbers.

Scroll through our gallery for the full rankings of the 20 debuts we've seen thus far. TheWrap will update this post as more new broadcast shows start.